Robust SOI process without footing for ultra high-performance microgyroscopes

A microgyroscope with flat bottom surfaces is fabricated by combining the SOI (silicon on insulator) method with the SBM (sacrificial bulk micromachining) process [1/spl sim/3]. Roughened bottom surfaces and loose silicon fragments are common problems in deep silicon RIE (Reactive Ion Etching) using SOI wafers. In this paper, the silicon fragments are removed and the roughened bottom surfaces are smoothed by the SBM process to achieve robust performance. A gyroscope is fabricated by the proposed method. The measured noise equivalent resolution is 0.0044/spl deg//sec, and the measured bandwidth is 12.8 Hz. The linearity of output is within 7.4% for /spl plusmn/50/spl deg//sec range.